The Yakovlev parametric cure rate model was used to study the age at which HIV-1 infection can be detected in nonbreast-fed infants and the independent predictors of transmission. Blood samples from 145 HIV-1-negative at birth infants born to HIV-1-positive untreated mothers were tested until 15 months. The age at actual detection and at potential detection providing daily tests was studied. The former was described using the Yakovlev model, and the cumulative probabilities of detection along time were calculated. Comparison of observed and predicted delays to positivity revealed the best representation of the age at which HIV becomes detectable among 8 Yakovlev models. Cumulative positive tests were as follows: 3 at 7 days, 10 at 15 days and 1 month, 17 at 3 months, and 18 at 15 months. The log-logistic model was the best-fitting one. The probability of onset of HIV-1 detectability was maximal at day 4. The mean and median age at which HIV becomes detectable were 12 and 6 days, respectively. Maternal CD4(+) cell count was associated with the risk of contamination [hazard ratio of low vs. high count 2.44; 95% (confidence interval): 1.15-6.67]. The model may explain HIV viremia dynamics and define the optimal antiretroviral regimens before randomized trial confirmation.